This invention relates generally to methods and apparatuses for applying lining structures to internal pipe surfaces, and more particularly relates to such methods and apparatuses wherein the linings include wound reinforcement filaments applied to internal tubular surfaces, and even more particularly relates to such methods and apparatuses wherein the linings are adapted and adaptable for use in the structural repair or remediation of degraded, damaged or leaking pipes, or such linings are adapted and adaptable to improve or upgrade qualities and characteristics of pipes prior to or after use or installation. In particular, the invention relates to apparatuses and methods for applying a unidirectional or bidirectional wound filament as a component of the multi-layer lining such that the lining possesses significantly increased hoop strength, beam bending strength and significantly reduces the potential for lining creep failure.
Typically, when municipal engineers, reliability engineers, and other end users search for rehabilitation or preventative maintenance solutions for water or industrial pipes, they highly prefer a “no dig”/trenchless solution which is much cheaper than the other types of methods so the users will not be constrained by the budgets. Many end users/clients would also prefer to spend money on a long-term pipe rehabilitation that closely duplicates the design of their original pipe system. Additionally, trenchless pipe rehabilitation has little negative impacts on the surrounding areas of the pipeline system since it only needs to make a few openings on the pipes to let the lining device get into them and most of the rehabilitation process is finished underground. There are many known compositions for internal pipe linings that provide improved properties or may be used to repair degraded or damaged pipes already in use. A cured-in-place pipe (CIPP) is one of several trenchless rehabilitation methods used to repair existing pipelines. In CIPP application, a resin-saturated felt tube made of polyester, fiberglass cloth or a number of other materials suitable for resin impregnation, is inverted or pulled into a damaged pipe first, then hot water, UV light, ambient cured or steam is used to cure the resin and form a tight-fitting, joint less and corrosion-resistant replacement pipe. Another important trenchless pipe rehabilitation method is referred to by the acronym SIPP, which stands for sprayed-in-place pipe, and application of the linings typically involves single or multiple passes of equipment applying one or more polymeric material layers to the interior of the pipe to form a “pipe-in-a-pipe”. There are, however, many problems or drawbacks associated with these lining methods.
While CIPP can repair a pipe with limited bend geometries, sags or deflections, this lining method cannot completely prevent wrinkling and stretching. Except for very common sizes, CIPP liners are not usually stocked and must be made specifically for each project. The liner material used for common sizes is normally a felted fabric (non-woven) or a bi-directional fabric and does not go around bends well without wrinkling and going out of round on corners. These wrinkles and defects can seriously reduce the liner strength against internal pressure loads and cause lining cracking and leaking issues. If the CIPP liner material is designed to have shorter circumference compared to the host pipe to remove wrinkles, this will create small annuluses or circumferential gaps between the liner and the host pipe into which water and/or effluent will infiltrate. In contrast, SIPP can spray polymeric lining materials directly onto pipe wall to create liners without wrinkles or folds, and this lining method can also get rid of annuluses or circumferential gaps between the liner and the host pipe via applying multi-layer liner structure (references if need). However, current SIPP technologies or any other pipeline rehabilitation technologies that utilize polymerics or more specifically thermosetting plastic materials as the structural member/barrier for the containment of pressurized fluid in an existing host pipe are constrained to the creep failure behavior of the polymeric materials under long term continuous stress. The large nonlinear stress-strain behavior of thermoplastic polyurethanes exhibits strong hysteresis, rate dependence and softening. There is no technology available in the SIPP market that can be applied to meet the structural requirements of AWWA M28 for class IV lining for pressure pipe. This holds true for many other pipe lining/pipe rehabilitation technologies as well. To overcome this issue many SIPP vendors try to increase the lining structure wall thickness which is not cost effective and it will reduce the cross-sectional diameter and the flow capacity of the rehabilitated pipes. The higher wall thickness needs more application time, which will add the potential for application error and mechanical failure while lining. Additionally, and maybe most importantly, current thermosetting polymers used in lining industries cannot be applied as one single thick membrane in large diameter pipes (diameter>10″) due to the exothermic reaction and the resulting tertiary stage induced by the internal stresses in the component. This results in the requirement of application in multiple layers which means multiple passes of the lining device which equates to significant increase in time and cost. Cost is not the only detriment to applying linings in multiple passes, other potential ramifications that can lead to failure are lack of inter-coat adhesion from passing the “recoat” window of the polymeric materials, infusing debris, dust or moisture from the outside environment via being pulled into the pipe over the preceding liner coat by the umbilical.
Creep is the tendency of a solid material to move slowly or deform permanently under the influence of mechanical stresses. It can occur as a result of long-term exposure to high levels of stress that are still below the yield strength of the material. The rate of deformation (strain rate) is a function of the material properties, exposure time, exposure temperature and the applied structural load. In the initial creep stage of loading of ductile material the creep rate decreases rapidly with time and then reaches the secondary stage where the deformation rate slows down and becomes steady unless exposed to high stresses that exceeds material yielding strength. In the tertiary stage, the strain rate exponentially increases with stress because of necking phenomena or internal voiding decreases the effective area of the material. Strength is quickly lost in tertiary stage while the material's shape is permanently changed and fractures will happen finally. Due to the nature of polymeric materials SIPP liners probably can meet the requirements of structure strength for short-term period but the material strength will decrease severely and the liner will start creeping till failure after a long-term use.
For potable water applications, the internal pipe lining is required to meet the American Water Works Association (AWWA) standards and in particular the standards set out below. Class IV linings are the strongest structural pipe linings of which the internal pressure and external load resistance capabilities do not rely on the material adhesion on the host pipe and the structural support from the pipe wall. This type of lining possesses the following characteristics:
4.2.4 Class IV Linings.
4.2.4.1 Class IV linings, termed fully structural or structurally independent, possess the following characteristics:
1. The lining has a long-term hoop strength which equal to or greater than the MAOP of the pipe to be rehabilitated. This hoop strength is tested independently from the host pipe.
2. The lining has long-term resistance to external and live loads and the resistance is independent from the host pipe.
3. The lining has a short-term hoop strength which equal to or greater than all short-term loads, such as sustained and surge (vacuum and occasional and recurrent surge) pressures and live loads even if these loads are in excess of the capacity of the host pipe. This hoop strength is tested independently from the host pipe.4.2.4.2 Class IV linings are sometimes considered to be structurally equivalent to new replacement pipe, although such linings will have markedly different properties in terms of buckling and longitudinal bending resistance than the original host pipe. These linings should be designed with adequate load resistance for all reasonable assumptions of loading conditions independent of the host pipe. By necessity, they will be of smaller internal diameters than the host pipe. However, their design should also consider practical implications to facilitate the continued service objectives of the host pipe such as the ability to provide water to service lines and mains without compromising the hydrostatic integrity of the overall lining system. (See AWWA M28, Chapter 11-3rd ed.)4.2.4.3 Class IV linings can also be used in circumstances similar to those for Class II and III, but their use is essential for host pipes suffering from generalized external corrosion where the mode of pipe failure has been, or is likely to be, longitudinal cracking. The host pipe suffers full loss of hoop strength because of the longitudinal crack. Other catastrophic modes (e.g. spiral cracks, circumferential cracks, a leadite style joint failure blow-out) can also happen on the pipe wall where more liner structural resistance is required than traditional hole spanning structural resistance.4.2.4.4 Some available pipe rehabilitation technologies can offer Class II, Class III and even Class IV linings, while a given lining system may be rated as Class IV for MAOP levels up to a threshold value and as a Class II and III system at higher pressures.
It is an object of this invention to provide an apparatus and methodology for producing an internally wound helical filament winding reinforcement on the interior surface of a tubular member. It is a further object to provide an apparatus and methodology for producing a multi-layer internal pipe lining structure having filament winding as a reinforcement element to increase the lining structure strength, more specifically hoop strength and to address the various problems and shortcomings of lining material creeping discussed above. It is a further object to provide an apparatus and methodology for applying a filament reinforcement comprising a UV-curable resin, a heat-curable resin or a combination thereof, and curing the filament reinforcement by exposing the filament to UV light and/or heat during the helical winding application process.